Flashback is a licensed Dreamcast release of the 1992 platforming game of the same name. It was released on September 30, 2017.
The source code of Flashback was converted to SDL, and this version was ported to the Dreamcast by Daniel Lancha, better known as Chui.
The Dreamcast version also has an option in the menu to play the various Sega Genesis and Sega Mega Drive versions. This is accomplished by an optimized version of Lancha's Gens4All emulator.